BABS1201 Lecture Notes - Lecture 1: Hydrogen Bond, Surface Tension, Chemical Polarity
16 May 2018
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Abundant elements in universe
Helium - abundant in universe, not that much on earth
• Medical purposes, cooling,
Oxygen and carbon - associate with life
• Carbohydrates
Why is water needed?
• Biological molecules assume shapes and functions in response to physical and chemical
properties of water
o Medium for most biochemical reactions are in water(aqueous environment)
o Cells 70-80% water
o Enzymes activity are predominantly in aqueous environments
• Reactions involving water supports life
o Hydration and dehydration reaction
• Catalyzed by different reactions
• Living organisms found where water is
Water
• 2 hydrogen atoms covalently bonded to an oxygen
o Oxygen more electronegative than hydrogen
o Creates a polar molecule
• Electrons are unequally shared
▪ Overall charge of the molecule is not evenly distributed
• Water can be ionized
• Hydrogen bonds
o H2S
o Gives different props
Water: cohesion
• Water molecules attract towards each other (due to polar molecule)
o When the water evaporates
• The hydrogen bonds causes other molecules to follow the movement upwards (in
trees)
Water: tension
• Water molecules near surface interact more with those below and adjacent to them
o Surface molecules can only interact with below and next tot them
• Surface of water there are more hydrogen bonds next to them
▪ Results in the surface of the water has more tension than further down
• Creates a film-like surface
• Premature babies have issues with water tension
o Water tension in the lungs can create problems with breathing
• Some injection can break the water tension so they can breathe
Water: dissolving ability
• Dissolves more substances than any other liquid
o A universal solvent
Fats and oils: hydrophobic
• Not charged at poles
• Not attracted to water
• Do not mix
Soap
• Have hydrophilic and hydrophobic ends
• Used to break up fat and oil droplets that are to be washed away
Water: heat
• Has a high specific heat
Water: expansion
• Water expands and floats when it freezes
• Has holes in structure due to hydrogen bonds
• So it’s less dense than most substances
▪ Floats on top of surfaces
Water: breaking down "fuels"
• We produce water when our bodies break down "fuels" to generate energy
What is life
• Smallest unit of organization that can perform all the activities essential for "life" is a a cell
• E.g. muscle cells
• Actions of organisms are based on
Cell characteristics
• Membrane
Characteristics of living things
• Reproduce
• Gro and develop
• Respond to environment
• Metabolize and use generated energy
Viruses and prions
• Viruses need a host to reproduce
• Cannot create their own energy
• Replicating proteins
• Cannot produce themselves
• Prions turns proteins into another prion
• A normal protein is made first then made into another prion
Diversity of life
• 1.8 millions species
3 domains of life
• Bacteria, archaea, eukaryotes
The importance of water:
• Water is the substance that makes all like possible on Earth
Document Summary
Helium - abundant in universe, not that much on earth: medical purposes, cooling, Oxygen and carbon - associate with life: carbohydrates. Water: cohesion: water molecules attract towards each other (due to polar molecule, when the water evaporates, the hydrogen bonds causes other molecules to follow the movement upwards (in trees) Water: tension: water molecules near surface interact more with those below and adjacent to them, surface molecules can only interact with below and next tot them. Some injection can break the water tension so they can breathe. Water: dissolving ability: dissolves more substances than any other liquid, a universal solvent. Fats and oils: hydrophobic: not charged at poles, not attracted to water, do not mix. Soap: have hydrophilic and hydrophobic ends, used to break up fat and oil droplets that are to be washed away. Water: heat: has a high specific heat. Water: expansion: water expands and floats when it freezes, has holes in structure due to hydrogen bonds.
